@@ -68,6 +68,19 @@ m_mouseTimer.setInterval(MOUSE_DISAPPEAR_TIMER);
 	setMouseTracking(true);
 }
 
+QSize Display::viewportSize() {
+	QSize s = size();
+	QSize ds = s;
+	if (isAspectRatioLocked()) {
+		if (s.width() * m_coreHeight > s.height() * m_coreWidth) {
+			ds.setWidth(s.height() * m_coreWidth / m_coreHeight);
+		} else if (s.width() * m_coreHeight < s.height() * m_coreWidth) {
+			ds.setHeight(s.width() * m_coreHeight / m_coreWidth);
+		}
+	}
+	return ds;
+}
+
 void Display::resizeEvent(QResizeEvent*) {
 	m_messagePainter.resize(size(), m_lockAspectRatio, devicePixelRatio());
 }
@@ -94,3 +107,8 @@ m_mouseTimer.stop();
 	m_mouseTimer.start();
 	event->ignore();
 }
+
+void Display::setSystemDimensions(int width, int height) {
+	m_coreWidth = width;
+	m_coreHeight = height;
+}

@@ -44,6 +44,8 @@ virtual bool isDrawing() const = 0;
 	virtual bool supportsShaders() const = 0;
 	virtual VideoShader* shaders() = 0;
 
+	QSize viewportSize();
+
 signals:
 	void showCursor();
 	void hideCursor();
@@ -68,6 +70,8 @@ virtual void mouseMoveEvent(QMouseEvent*) override;
 
 	MessagePainter* messagePainter() { return &m_messagePainter; }
 
+	void setSystemDimensions(int width, int height);
+
 private:
 	static Driver s_driver;
 	static const int MOUSE_DISAPPEAR_TIMER = 1000;
@@ -76,6 +80,8 @@ MessagePainter m_messagePainter;
 	bool m_lockAspectRatio;
 	bool m_filter;
 	QTimer m_mouseTimer;
+	int m_coreWidth;
+	int m_coreHeight;
 };
 
 }

@@ -73,6 +73,10 @@ m_drawThread->start();
 	mCoreSyncSetVideoSync(&m_context->sync, false);
 
 	lockAspectRatio(isAspectRatioLocked());
+	unsigned width, height;
+	thread->core->desiredVideoDimensions(thread->core, &width, &height);
+	setSystemDimensions(width, height);
+
 	filter(isFiltered());
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
 	messagePainter()->resize(size(), isAspectRatioLocked(), devicePixelRatioF());

@@ -21,6 +21,7 @@ }
 
 void DisplayQt::startDrawing(mCoreThread* context) {
 	context->core->desiredVideoDimensions(context->core, &m_width, &m_height);
+	setSystemDimensions(m_width, m_height);
 	m_backing = std::move(QImage());
 	m_isDrawing = true;
 }
@@ -58,14 +59,7 @@ if (isFiltered()) {
 		painter.setRenderHint(QPainter::SmoothPixmapTransform);
 	}
 	QSize s = size();
-	QSize ds = s;
-	if (isAspectRatioLocked()) {
-		if (s.width() * m_height > s.height() * m_width) {
-			ds.setWidth(s.height() * m_width / m_height);
-		} else if (s.width() * m_height < s.height() * m_width) {
-			ds.setHeight(s.width() * m_height / m_width);
-		}
-	}
+	QSize ds = viewportSize();
 	QPoint origin = QPoint((s.width() - ds.width()) / 2, (s.height() - ds.height()) / 2);
 	QRect full(origin, ds);
 

@@ -686,9 +686,10 @@ }
 
 void Window::mouseMoveEvent(QMouseEvent* event) {
 	QSize dimensions = m_controller->screenDimensions();
+	QSize viewportDimensions = m_display->viewportSize();
 	QSize screenDimensions = m_screenWidget->size();
-	int x = dimensions.width() * event->x() / screenDimensions.width();
-	int y = dimensions.height() * event->y() / screenDimensions.height();
+	int x = dimensions.width() * (event->x() - (screenDimensions.width() - viewportDimensions.width()) / 2) / viewportDimensions.width();
+	int y = dimensions.height() * (event->y() - (screenDimensions.height() - viewportDimensions.height()) / 2) / viewportDimensions.height();
 	m_controller->cursorLocation(x, y);
 	event->accept();
 }
@@ -698,9 +699,10 @@ if (event->button() != Qt::LeftButton) {
 		return;
 	}
 	QSize dimensions = m_controller->screenDimensions();
+	QSize viewportDimensions = m_display->viewportSize();
 	QSize screenDimensions = m_screenWidget->size();
-	int x = dimensions.width() * event->x() / screenDimensions.width();
-	int y = dimensions.height() * event->y() / screenDimensions.height();
+	int x = dimensions.width() * (event->x() - (screenDimensions.width() - viewportDimensions.width()) / 2) / viewportDimensions.width();
+	int y = dimensions.height() * (event->y() - (screenDimensions.height() - viewportDimensions.height()) / 2) / viewportDimensions.height();
 	m_controller->cursorLocation(x, y);
 	m_controller->cursorDown(true);
 }
@@ -710,9 +712,10 @@ if (event->button() != Qt::LeftButton) {
 		return;
 	}
 	QSize dimensions = m_controller->screenDimensions();
+	QSize viewportDimensions = m_display->viewportSize();
 	QSize screenDimensions = m_screenWidget->size();
-	int x = dimensions.width() * event->x() / screenDimensions.width();
-	int y = dimensions.height() * event->y() / screenDimensions.height();
+	int x = dimensions.width() * (event->x() - (screenDimensions.width() - viewportDimensions.width()) / 2) / viewportDimensions.width();
+	int y = dimensions.height() * (event->y() - (screenDimensions.height() - viewportDimensions.height()) / 2) / viewportDimensions.height();
 	m_controller->cursorLocation(x, y);
 	m_controller->cursorDown(false);
 }